Low Rank and Shallow Coal
Low rank coals are particularly suited to bioconversion, and represent the greatest opportunity for value uplift, by turning low value coal into high value gas resources.
Verso has been investigating multi-stage bioconversion for the last 4 years and has developed a method whereby the coal is partially solubilised underground and the fluid stream recovered to surface. The process is controlled through a surface to inseam intercept well, which creates a flow loop through the ground.
Carbon rich liquids are processed in a second stage wastewater bioreactor, which produces gas. Cleaned water is able to be re-used through the looped system to sustain the process without depletion of groundwater levels.